Reinforcing asbestos-cement sheets



Dec. 11, 1951 F. L. NASH 2,578,581

REINFORCING ASBESTOS-CEMENT SHEETS Original Filed Aug. 18, 1948 5Sheets-Sheet 1 Inventor 5am? dew/yard Was/2 Attorney Dec. 11, 1951 F. L.NASH 2,573,531

REINFORCING ASBESTOS-CEMENT SHEETS Original Filed Aug. 18, 1948 3Sheets-Sheet 2 Inventor Fwy/ Lama/m Nash Dec. 11, 1951 F. L. NASH2,573,581

I REINFORCING ASBESTOS-CEMENT SHEETS Original Filed Aug. 1a, 1948 sSheetsSheet s Patented Dec.-ll, 1951 REINFORCING ASBESTOS-CEMENT SHEETSFrank Lennard Nash, Widnes, England, assignor to Turners Asbestos CementCompany Limited, Rochdale, England, a British company Originalapplication August 18, 1948, Serial No. 44,828. Divided and thisapplication June 22, 1950, Serial No. 169,755. In Great Britain 00-tober 20, 1947 4 Claims.

1 The present invention rel-ates in general to the internalreinforcement of objects, and it deals more particularly with thereinforcement of asbestos cement sheets or the like.

chek type in which successive laminations of the moist material aretransferred from a carrier band to the cylinder (which is commonly knownas aforming bowl). When the laminations have built up to the desiredthickness a cut must be made parallel to the axis so that the laminatedcovering on the forming bowl can be detached from it and removed as asheet. A groove is commonly made along the bowl and may be called theparting-off line, a knife being run along this groove by the operator tomake the cut.

The cutting of a sheet of asbestos cement while it is still in a plasticstate is a simple matter. However, the sheets must often be internallyreinforced and the reinforcement is introduced while the material isstill on the forming bowl, being inserted between two laminations. Tocut a reinforced sheet is not simple, as the reinforcement commonlyconsists of metal, and it is found to be practically impossible to cutthrough a reinforced sheet while the asbestos-cement is still plastic.It is at this stage, however, that it is desirable to cut any sheet toits final size.

Each length of reinforcement preferably takes the form of a number ofparallel wires extending circumferentially around the rotating cylinder.Wm. H. Rooksby application Serial No. 673,791 filed June l, 1946,describes a form of apparatus for feeding reinforcing wires lengthwiseto the rotating cylinder of a machine of the Hatschek type so that'theyare located on the cylinder in predetermined positions in relation tothe parting-off line. More particularly, each wire is wrapped around thecylinder with its opposite ends disposed in spaced-apart relationship oneither side of the parting-off line; thus, the asbestos cement sheet canbe cut from the cylinder without having to cut through the wires.

Now the length of the finished sheet is determined by the diameter ofthe forming bowl, and when it is desired to vary the length the formingbowl must be changed for another of a different diameter. It isinconvenient to have to provide a large number of forming bowls to allowsheets of different lengths to be made, and short sheets are sometimesmade by using a forming bowl large enough to produce a long sheet andthen cutting this long sheet into shorter lengths. In practice a longsheet is generally cut into two short sheets and to provide a largevariety of different lengths of sheet, the lengths of these two shortsheets may vary considerably in relation to one another. For instance,if a forming bowl is used which gives a sheet 12 feet long this sheetmay be cut in half to give two lengths of 6 feet each or it may be cutto give sheets of 5 feet and 7 feet or yet again'it may be cut to givesheets of 8 feet and 4 feet.

It is an object of the present invention to provide a method for forminglong reinforced sheets which may easily be cut in shorter lengths.

Another object is to provide a method for forming a sheet of thecharacter disclosed in the aforementioned Rooksby application Serial No.673,791, except that the continuity of the reinforcing wires isinterrupted along one or more lines extending crosswise of the sheetintermediate its ends thereby to facilitate cutting of the sheet intoshort lengths.

According to the present invention short reinforced sheets are made bybuilding up a coating on a rotating cylinder to form a long sheet andintroducing lengths of reinforcement into the material to wrap aroundthe cylinder, these lengths of reinforcement being spaced a shortdistance apart circumferentially so'as to leave at least two shortcircumferential lengths of the built-up coating unreinforced. One ofthese unreinforced lengths includes the parting-oil line, that is tosay, the line along which the operator makes the out, whether or not itis defined by a groove on the forming bowl, and the other (or eachother) includes the line (or lines) along which the long sheet is out toform short sheets. The long sheet can therefore be cut into short sheetswithout it being necessary to cut through the reinforcement. The presentapplication may advantageously be carried out by modifying the apparatusdisclosed in Rooksby application Serial No. 673,791, in a mannerdisclosed and claimed in my co-pending application Serial No. 44,828. Toassist an understanding of the present invention one such apparatussuitable for making reinforced sheets each to be cut into two shortersheets will now be described by way of example with reference to theaccompanying drawings, in which:

Figure 1 is a side elevation-of the apparatus.

Figure 2 is a, plan view of the apparatus shown in Figure 1, and

Figure 3 shows diagrammatically the positions of the reinforcing wireson the rotating cylinder and in the finished sheet,

Figure 4 is an enlarged detail view taken along the line 4-4 of Figure1, in the direction of the arrows, I

Figure 5 is a detail view of the cam operated switches and theassociated manual control therefor, and

Figure 6 is a sectional elevation taken alon the line 6-4 of Figure 5 inthe direction of the arrows.

In the apparatus shown, an endless felt band I, carrying a layer ofasbestos cement slurry passes over a roller 2 into contact with a rotarycylinder or forming bowl 3. The asbestos cement is transferred to theforming bowl at the point where the band passes through the nip betweenthe forming bowl and a pressure roller 4, and as the operation proceedssuccessive laminations are built up on the bowl. When the desiredthickness has been attained the coating-is removed from the bowl as theresult of a cut made by a knife guided by a groove or partingoff line 5on the surface of the bowl, the coating then peeling off in the form ofa flat sheet during the subsequent revolution of the bowl.

Two separate feeding devices are provided, one for each set of wiresconstituting a length of reinforcement. The devices include a lower setof inclined guide-tubes 6 and an upper set of guide-tubes I arrangedimmediately above the tubes 6 and inclined at a slightly greater angleto the horizontal, so that the two sets of tubes converge towards theforming bowl, being supported by brackets 8 and 9. The tubes havefunnel-shaped mouths l and are arranged in alignment with two furthersets of tubes II and I2 which also have funnel-shaped mouths l3 and aresupported by brackets i4 and IS.

A reinforcing wire of the appropriate length is placed in each of thetubes H and I2 and extends into the corresponding tube 6 or I, beingprevented from passing beyond the end of the tube by plates H3 and I1closing the ends of the tubes 6 and 1 respectively. These plates slidein guides l8 and i9 and are provided with ports 20 corresponding to theends of the tubes. The plates are pulled into the position in which theports -2|] register with the ends of the tubes by wires 2| and 22against the action of tension springs 23 and 24 which return the platesto the position of non-register when the tension is released from thewires. The wires 2| and 22 pass over pulleys 25 and 26 and 21 and 28respectively and are attached to the armatures 29 and 30 of solenoids 3|and 32. Thus when the solenoids are energised the armatures areattracted and apply tension to the wires 2| and 22 to move the plates I6and I1 into the position in which the ports register with the ends ofthe tubes and as soon as the solenoids are de-energised the platesreturn to the position of non-register.

When wires are in-position in the tubes each is exposed over a shortaxial length corresponding to the gap between the sets of tubes 6 and Hor I and I2 as the case may be. Each wire is acted on frictionally atthis point by a pair of rollers 33 and 34 or 35 and 36 which are drivenfrom an electric motor 31 and serve to urge the wire downwards along thetube. The operation of these rollers is exactly analagous to that of therollers 23 and 24 shown in Figures and 6 of application Serial No.673,791.

As soon as either solenoid 3| and 32 is energised to move thecorresponding plate into the registering position the wires .in thecorresponding set of tubes are fed forwardunder the influence of thefriction rollers, being guided by a sheet-metal extension-piece 38 onthe end of the tubes so that they wrap smoothly around the forming bowl3 and lie in-the positions shown in Figure 3.

Each of the solenoids is energised by way f an electrical circuit whichincludes a cam-operated switch. A switch 39 controls the solenoid 3| anda switch 40 the solenoid 32. The switches are carried on a lever arm 4|pivoted at 42 and are actuated by cams 43 and 44 carried on an extension45 of the main shaft of the forming bowl. In its free position the arm4| hangs so that the switches are clear of the respective cams. but itmay be moved by the operator into a position (shown dotted in Fig. 5) inwhich it is in contact with a stop 46 and in which the switches may beactuated by the projections on the respective cams.

The cam 43 which serves to initiate the feed of the wires in the set oftubes 6 is set on the shaft to time the feeding so that the leading endsof the wires lie close to the parting-off line 5. Since, whatever therelative lengths of the two shorter sheets into which the sheet is to becut, the end of the reinforcement must lie close to the end of thesheet, the setting of the cam 43 will be constant and will not requirealteration. The position of the ends of the second set of wires in thetubes 1 will, however, depend on the relative lengths of the two shortersheets and the angular position of the cam 44 must therefore be adjustedaccordingly.

In use the operator allows the coating to build up until it has reachedapproximately half the desired thickness. He then moves the lever arm 4|into contact with the stop to bring the surfaces of the cams 43 and 44into contact with the respective switches. The two sets of reinforcingwires are then fed to the forming bowl at the appropriate instants andwrap smoothly around it. The coating then continues to build up on topof the reinforcing wires until the final thickness is reached, when thecoating is removed from the forming bowl in the usual manner.

Although the invention is primarily useful in its application to themanufacture of asbestoscement sheets, it may also be applied to themanufacture of sheets from any similar material which will set rigidfrom the plastic state, containing for example other fibres or anotherbinding agent.

This application is a division of my copending application Serial No.44,828, made August 18, 1948.

I claim:

1. The process of forming reinforced sheets comprising the steps ofwindin a web of thin plastic material on a rotary cylinder to form amulti-layer tube, placing a first reinforcin segment whose length is afractional part of the circumference of the tube between the web and thelast layer already formed on the tube, the leading end of said firstreinforcing segment being positioned adjacent the point where the webreaches the tube, continuing the winding of the web on the cylinderthrough part of a revolution to wrap the first reinforcing segmentaround the tube, spacing the leading end of a second reinforcing segmentwhose length is slightly less than the difference between thecircumference of the tube and the length of the first segment slightlybehind the trailing end of said first segment,

continuing the winding to wrap said second segment about the tubewhereby said segments are located between two of the layers and havetheir adjacent ends spaced slightly from one another to provide the tubewith two circumferentially spaced unreinforced parts, cutting said tubelongitudinally through one of said unreini'orced parts, and flatteningout the tube to form a sheet.

2. The process of forming reinforced sheets comprising the steps ofwinding a web of thin plastic material on a rotary cylinder to form amulti-layer tube, placing a first reinforcing segment whose length is afractional part of the cireumference of the tube between the web and thelast layer already formed on the tube, the leading end of said firstreinforcing segment being positioned adjacent the point where the webreaches the tube, continuing the winding of the web on the cylinderthrough part of a revolution to wrap the first reinforcing segmentaround the tube, spacing the leading end of a second reinforcing segmentwhose length is slightly less than the difference between thecircumference of the tube and the length of the first segment slightlybehind the trailing end of said first segment, continuing the winding towrap said second segment about the tube whereby said segments arelocated between two of the layers and have their adjacent ends spacedslightly from one another to provide the tube with two circumferentiallyspaced unreinforced parts, cutting said tube longitudinally through oneof said unreinforced parts, flattening out the tube to form a sheet, anddividing the sheet into lengths by cutting through the otherunreinforced part.

3. The process of forming reinforced sheets comprising the steps ofwinding a web of thin plastic material on a rotary cylinder to form amulti-layer tube, placing a first set of parallel wires having a commonlength equal to a fractional part of the circumference of the tubebetween the web and the lastlayer already formed on the tube, the wiresbeing aligned longitudinally of the web and having their leading endspositioned adjacent the point where the web reaches the tube, continuingthe winding of the web on the cylinder through part of a revolution towrap the first, set of wires around the tube, spacing the leading endsof a, second set of parallel wires having a common length slightly lessthan the difference between the circumference of the tube and the lengthof the first wires slightly behind the trailing ends of said firstwires, continuing the winding to wrap said second set of Wires about thetube whereby said sets of wires are located between two of the layersand have their adjacent ends spaced slightly from one another to providethe tube with two circumferentially spaced unreinforced parts, cuttingsaid tube longitudinally through one of said unreinforced parts, andflattening out the tube to form a, sheet.

4. The process of forming reinforced sheets comprising the steps ofwinding a web of thin plastic material on a rotary cylinder to form amulti-layer tube, placing a first set of parallel wires having a commonlength equal to a fractional part of thecircumierence of the tubebetween the web and the last layer already formed on the tube, the wiresbeing aligned longitudinally of the web and having their leading endspositioned adjacent the point where the web reaches the tube, continuingthe winding of the web on the cylinder through part of a revolution towrap the first set of wires around the tube, spacing the leading ends ofa second set of parallel wires having a common length slightly less thanthe diflerence between the circumference of the tube and the length ofthe first wires slightly behind the trailing ends of said first wires,continuing the winding to wrap said second set of wires about the tubewhereby said sets of wires are located between two of the layers andhave their adjacent ends spaced slightly from one another to provide thetube with two circumferentially spaced unreinforced parts, cutting saidtube longitudinally-through one of said unreinforced parts, flatteningout the tube to form a sheet. and dividing the sheet into lengths bycutting through the other unreinforced part.

FRANK LENNARD NASH.

REFERENCES CITED UNITED STATES PATENTS Name Date Wade Oct. 22, 1907Number

1. THE PROCESS OF FORMING REINFORCED SHEETS COMPRISING THE STEPS OFWINDING A WEB OF THIN PLASTIC MATERIAL ON A ROTARY CYLINDER TO FORM AMULTI-LAYER TUBE, PLACING A FIRST REINFORCING SEGMENT WHOSE LENGTH IS AFRACTIONAL PART OF THE CIRCUMFERENCE OF THE TUBE BETWEEN THE WEB AND THELAST LAYER ALREADY FORMED ON THE TUBE, THE LEADING END OF SAID FIRSTREINFORCING SEGMENT BEING POSITIONED ADJACENT THE POINT WHERE THE WEBREACHES THE TUBE, CONTINUING THE WINDING OF THE WEB ON THE CYLINDERTHROUGH PART OF A REVOLUTION TO WRAP THE FIRST REINFORCING SEGMENTAROUND THE TUBE, SPACING THE LEADING END OF A SECOND REINFORCING SEGMENTWHOSE LENGTH IS SLIGHTLY LESS THAN THE DIFFERENCE BETWEEN THECIRCUMFERENCE OF THE TUBE AND THE LENGTH OF THE FIRST SEGMENT SLIGHTLYBEHIND THE TRAILING END OF SAID FIRST SEGMENT, CONTINUING THE WINDING TOWRAP SAID SECOND SEGMENT ABOUT THE TUBE WHEREBY SAID SEGMENTS ARELOCATED BETWEEN TWO OF THE LAYERS AND HAVE THEIR ADJACENT ENDS SPACEDSLIGHTLY FROM ONE ANOTHER TO PROVIDE THE TUBE WITH TWO CIRCUMFERENTIALLYSPACED UNREINFORCED PARTS, CUTTING SAID TUBE LONGITUDINALLY THROUGH ONEOF SAID UNREINFORCED PARTS, AND FLATTENING OUT OF THE TUBE TO FORM ASHEET.